I-I can't believe it, he flooded that aquarium with tar... all those poor dead fish! As much as I hate to see what heinous crime this fiend will do next, you should probably keep on his tail... someday the people will know the truth thanks to your pictures.
― Bentley, after witnessing Octavio flood an aquarium with tar[src]
Sly and Bentley need photographic evidence that Don Octavio is behind Venice's tar epidemic. With photos catching him in the act, the cops will be able to prosecute him and put an end to his operation. As the two are talking, the Don comes into sight and begins pumping tar into a nearby fountain. Sly takes a photo of him, after which Octavio heads off and Sly follows.
Octavio pollutes both a birdbath and a water wheel pouring into the canal, before arriving at and polluting an aquarium full of fish. Snapping photos of all three, Sly is prompted by Bentley to continue following Octavio to see what "heinous crime" he will next commit. Octavio arrives at not another valve, but a Ferris wheel. After getting on it, the Don makes a call, which Sly eavesdrops on by hanging onto the side of the Ferris wheel car.
The person on the other end of the line is Giovanni, the presumed creator of the Ferris wheel. Octavio tells him how the Ferris wheel is pumping the tar fast and that nobody expects a thing, but that he is unsure if it will be enough "to get things ready for [his] opera recital." Giovanni confirms that it will, and Octavio proclaims that there will be opera fans again, "one way or the other."
Octavio hangs up and heads off on other business, which allows Sly to break open the Ferris wheel's control panel. Bentley arrives shortly and rewires the engine, causing it to speed up. The wheel breaks off of the hub and crushes one of Octavio's goons in the process. With the massive pump destroyed it's job complete.
- If Sly wears the Venice disguise when replaying this mission, Don Octavio sees through it.
- Although Bentley mentions that dead fish are in the aquarium that Octavio pollutes, none of them can actually be seen.